Conventionally, as an optical disc on which such as music data are recorded, for example, a CD (Compact Disc) is widely used.
The disc for music CDs has recorded therein music data such as of non-compressed and the usual CD disc has a diameter of 12 cm. To the contrary, in order to improve the portability, it is often practiced that the music data is compressed and the compressed music data is digitally dubbed into an MD (Mini Disc) to enable carrying on of same.
Recently, by performing digital dubbing into a recording medium such as a non-volatile memory or an HDD (Hard disc drive) which have further larger capacities than the MD, a unified administration of music pieces of not only a piece of CD but over a plurality of CDs, and thus, the utilization of portable audios, home audios, and car audios, which reproduce same are spread.
As devices which perform dubbing of music data from the CD, PCs (personal computes) are widely used. However, it is not limited thereto. For example, there are a lot of systems which can perform directly dubbing of music data without employing a personal computer by an audio apparatus such as a stereo component itself, and these systems are accepted in the market in view of easiness of its operation.
FIG. 26 is a construction diagram of such a conventional system which can prevent deterioration of sonic quality which arises due to that the digital signal is once converted into an analog signal and then it is again returned to the digital signal by performing a digital dubbing, i.e., performing dubbing in the state of the digital signal as it is.
In FIG. 26, the disc reproduction device 11 is one which is included in stereo components which can perform directly a digital dubbing by themselves, and which perform reproduction from the optical disc 10 and output the reproduced data. The buffering control device 181 performs a pre-processing of digital dubbing, which comprises receiving the reproduced data from the disc reproduction device 11 and temporarily buffers the data into a memory 18 such as a DRAM. The system control part 19 gives an instruction for buffering to the buffering control device 181.
The reproduction part 12 in the disc reproduction device 11 carries out a series of operations such as a servo control for controlling the pick-up or the spindle motor for the optical disc 10, the digital conversion, demodulation, or the error correction of the signal which was read out from the pick-up. In addition, the transmission part 13 in the digital reproduction device 11 includes an output device for transferring the reproduced data which is reproduced by the reproduction part 12 to another device such as a portable audio system.
The transfer of the data reproduced from the disc reproduction device 11 is generally performed in a serial type which utilizes three lines of a word clock, a bit clock, and a reproduced data line. Particularly, in a reproduction of a music CD, a format in which left and right two channels of music data are transferred with referring to the word clock which is alternated with “H” and “L” as making 16 bit samples as a unit as shown in FIG. 27 is widely used. That is, in accordance with the word clock being “H” or “L”, whether the data of 16 bits constituting the music data correspond to either of left and right channel is distinguished. Further, included in the reproduced data which is reproduced from CD, separately from the music data as main data, is sub data for selectively reproducing a disc, i.e., which is, for example one for selectively reproducing a desired music piece from a plurality of music pieces which are recorded in the CD, and such sub data is also transferred when that data is required at the receiver's side.
FIG. 28 is a diagram illustrating an example of a format of data when transferring the sub data and the main data through the same path. The receiving part 182 shown in FIG. 29 corresponds to the receiving part 15. By this construction, the sub data can be transmitted via the same path as the main path, and the number of the data transfer paths can be minimized easily (patent document 1).
The construction of the receiving part which receives this data is shown in FIG. 29.
In FIG. 29, included in the reproduced data which is received in the receiving part 182 are the main data and the sub data, and the main data is transferred to the buffering control part 184 and the sub data is transferred to the sub data register 183, respectively.
More particularly, the shift register 182a of a 17 bit length which is included in the receiving part 182 successively shifts the reproduced data which is successively inputted to its serial input therein synchronized with the bit clock, and when the data of 17 bits are stored, outputs and transfers the stored data from its parallel output of the shift register 182a to the receiving data register 182b. The receiving data register 182b outputs its top bit to the sub data register 183 as sub data as well as remaining data to the buffering control part 184 as main data. By this construction, the main data and the sub data are outputted with synchronized with each other. Here, the receiving register 182b employs the word clock and its inverted clock inverted by the inverter 182c as clocks.
FIG. 30 illustrates a construction of the receiving part 13 of the disc reproduction device 11, which corresponds to the receiving section 182.
In FIG. 30, the main data and the sub data from the reproduction part 12 which are received in the transmission part 13 are stored in the transmission data register 13a. Then, the sub data serves as the top bit and the main data is added thereto at thereafter. These main data and the sub data are transmitted to the shift register 13b in parallel and outputted directed to the receiving part 182 with one by one bit synchronized with the bit clock that is generated by the bit clock generator part 13e. The word clock which alternates being “H” and “L” with 17 bits unit of the bit clock is generated by the word clock generator 13d and is outputted directed to the receiving part 182. Further, the bit clock of 17 bits is generated each time when the main data of 16 bits is inputted by the bit clock generator 13e. Here, the transmission data register 13b employs the word clock and its inverted clock inverted by the inverter 13c as clocks.
In addition, the sub data in the sub data register 183 is checked by the system control part 19 shown in FIG. 26, and thereby the reproduction position on the disc can be recognized and, on the basis of these information the instruction for buffering to the buffering control part 184 is performed. On the basis of the buffering instruction from the buffering control part 19, the buffering of the main data into the memory 18 is performed by the buffering control part 184b. 
Then, the data which is once stored in the memory 18 is again read out, and after the compression processing is performed by the compression part which is not shown, the writing in into a recording medium in another device such as a portable audio system such as an MD or HDD is performed.
FIG. 31 is a diagram illustrating an example of another construction of a conventional system which performs dubbing of music data such as from a CD.
In the disc reproduction device shown in FIG. 31, a shock proof control part 264 for preventing a sound jumping at such as vibration is added in the disc reproduction device 11 shown in FIG. 26 so that the reproduced data which is reproduced by the reproduction part 262 is once stored into the second memory 265 such as a DRAM by the shock proof control part 264, and thereafter the reading out of the data is performed to be transferred by the transmission part 263. Here, in order that the main data and the sub data are transferred as reproduced data as shown in FIGS. 28 and 31, it is required that the sub data which corresponds to the main data are written in into and read out from the second memory 265.    Patent Document 1: Japanese Published Patent Application No. 2002-261716 (page 5-6, FIGS. 1 and 2)